Title (fr)

Publication

Application

Priority

US 9706975 W 19970425

US 63811696 A 19960426

Abstract (en)

[origin: WO9741067A1] A compact dissolved air flotation (DAF) clarifier (10, 10') and clarification process utilize three zones for clarification which operate in sequence in a single clarifier (I, II, III). Raw water with suspended solid contaminants enters a flocculator (14) at the center of an annular tank (16) where microscopic air bubbles introduced to the inflow float flocked contaminants to form a floating sludge layer (12). A first clarification (I), calming and degassing occur here. The water then flows radially outwardly into the tank (16) where further quiet clarification (II) occurs. A third level (III) of clarification occurs in a lower portion (16b) of the tank, specifically, in a set of plate-like lamellae (18), radial (18a) and conical (18b), which form inclined channels (52) where a final clarification occurs. The bottom wall (16c) of the tank has a set of apertures (54) which allow a gravity flow of clarified water (40) through a layer (44) of pressurized gas to an underlying collection compartment (38). Level sensors (100, 124) control a valve (42) in the clarified outflow line (24) and an air bleed from the pressurized gas layer to regulate liquid levels in the clarifier. A set of rotating paddles (78) push the sludge layer (12) up a ramp (81) to an inclined discharge conduit (82). Alternatively, a suction head (84) with a mechanical skimmer (84b) sweeps around the tank to draw the sludge through a central hollow pipe (89) to a discharge conduit (82'). An offset drive (56) operating through a belt (64) rotates the sludge removal mechanism (58, 58') and the lamellae (18).